In a fuel injection valve of an engine, as a particle diameter of an injected fuel becomes smaller, evaporation of the fuel is accelerated. At the same time, the amount of fuel adhering to an inner wall of the engine is reduced to reduce the amount of exhaustion of uncombusted fuel. As a result, a fuel consumption efficiency (fuel efficiency) of the engine is improved to reduce the amount of emission of a harmful gas. As means for atomizing the fuel to be injected, there have been proposed various types of means to appropriately design a shape of an injection hole of the fuel injection valve to reduce a thickness of a film of the injected fuel so as to achieve the atomization. For example, there is disclosed a related art fuel injection valve including two cylindrical injection holes with inclined center axes, which are provided in proximity to each other so that flows of the fuel injected from the injection holes are made to collide against each other to form a liquid film so as to atomize the fuel to be injected (for example, see Patent Literature 1).
There is also disclosed another fuel injection valve including a large number of slit-like injection holes extending in a radial direction, which are arranged in a star-like pattern, in which the flows of the fuel injected from the injection holes form a large number of flat flows having a small fuel liquid layer thickness to atomize the fuel to be injected (for example, see Patent Literature 2). There is also disclosed a further fuel injection valve including a large number of slit-like injection holes arranged in a concentric manner so that the fuel injected from the injection holes forms a pear-like fuel particle cloud to atomize the fuel to be injected (for example, see Patent Literature 3).
Further, there is disclosed a further fuel injection valve including a large number of slit-like injection holes, in which a width of each of the injection valves in a long axis direction of the slit is increased toward an outlet of the injection hole to form a flat flow so as to atomize the fuel to be injected (for example, see Patent Literature 4). Further, there is disclosed a further fuel injection valve including a large number of slit-like injection holes, in which turbulent generating means formed by a concave-shaped groove is provided on an inner wall of each of the injection holes to generate a disturbance in a passing fuel flow so as to atomize the injected fuel (for example, see Patent Literature 5). Further, there is also disclosed a fuel injection valve including injection holes provided across steps formed inside a flow path, in which the fuel is made to collide against an inner surface of each of the injection holes to form a further liquid film so as to achieve the atomization (for example, see Patent Literature 6).